Hitachi IGBT Module Application Manual

ge

follows the relationship indicated below (where

f

1

and

f

2

represent functions):

Equation 40:

Equation 41:

v

ge

v

ge

f

1

(I

C

)

f

2

(1/T

J

)

Here,

T

Dâ€™

module junction temperature. In the case of the Hitachi GS Series, it is sufficient to consider (at I

C

approximately 0 A and T

j

= 125 deg. C.) that V

th

(on) = 5V and V

th

(off) = 5V as the bottom limits.

Note:

1) In a module consisting of IGBT chips in parallel, the gate of each

IGBT chip is connected to a resistor chip in series. These resistors

are generally composed of semiconductor resistors, so that these

temperature factors are rather high: about 1% per degree. If the

module has a high temperature, the R

G

in Equation 39 becomes

equivalently high and the dead time

T

Dâ€™

may become short.

2) When extremely narrow control is conducted, and in the case of

narrow off control, for example, voltage applied to the gate may not

reach the source voltage of the driver, may be applied only at close

to 0 Volts, and may be transferred to turn-OFF. Thus, if the gate

voltage does not reach the source voltage of the driver, the t

d

(on)

and t

d

(off) can be determined by performing calculations with the

V

GN

and V

GP

replaced with real values applied to the gate in

Equations 35 and 36.

Note:

5.7.3.3

Determinations of Gate Charge Values

The value for Q

GC

in Equation 39 can be determined for each of the rated collector currents by means

of Figure 46.

Figure 46. Gate Charge Q

GC

Values

Because logic dead time varies due to several factors, use dead time values obtained in Equation 39 to

establish a setting that assures sufficient leeway.

42